1. Field of the Invention
The invention relates generally to computer networks technology. More particularly, this invention relates to the management of client requests in client-server based networks.
2. Description of the Related Technology
Internet Protocol (IP) is a network layer protocol used by many corporate networks, government networks, and the public Internet worldwide. IP network layer supports many personal, technical, and business applications, such as electronic mail, electronic fund transfers, medical records processing, and similar data transfers. IP is a connectionless network layer protocol that performs addressing, routing and control functions for transmitting and receiving datagrams over a network. The network layer routes packets from source to destination. An IP datagram is a data packet comprising a header part and a data part. The header part includes a fixed-length header segment and a variable-length optional segment. The data part includes the information being transmitted over the network. As a connectionless protocol, IP does not require a predefined path associated with a logical network connection. Hence, IP does not control data path usage. If a network device or line becomes unavailable, IP provides the mechanism needed to route datagrams around the affected area.
Transmission Control Protocol (TCP) is a transport layer protocol used to provide a reliable, connection-oriented, transport layer link among computer systems. The network layer provides services to the transport layer. Using a two-way handshaking scheme, TCP provides the mechanism for establishing, maintaining, and terminating logical connections among computer systems. TCP transport layer uses IP as its network layer protocol. Additionally, TCP provides protocol ports to distinguish multiple programs executing on a single device by including the destination and source port number with each message. TCP performs functions such as transmission of byte streams, data flow definitions, data acknowledgments, lost or corrupt data re-transmissions, and multiplexing multiple connections through a single network connection. Finally, TCP is responsible for encapsulating information into a datagram structure.
Interprocess communication (IPC) transactions may occur across various computer networks using a variety of communication models. The dominant model for communicating between two computers is based on a client-server relationship. Using this relationship, a client computer (the “client”) issues one or more command requests to a server computer (the “server”). The server fulfills client command requests by accessing necessary resources pursuant to the request, and executes applicable commands accordingly. The TCP/IP standard mandates IPC transactions to conform to this client-server relationship, which leads to a problem. As the number of clients increases, the ability of the server to meet the demands of clients diminishes. Hence, for instance, command requests from multiple clients for the transfer of files from same resource (e.g., server) require more time to fulfill by the host server. More importantly, multiple command requests destined to the same server creates data path congestion and slows down the network.
Several methods were used to deal with this congestion in the technology. The first method involves preallocating buffers for packets by dedicating memory space at intermediate (i.e., on route) servers to temporarily hold the packets. This method is costly to network operators. A second method involves discarding packets when there is no space to receive the packet at the destination host, or if a packet is not captured before a predetermined duration of time (e.g., 255 seconds). This method causes delay in the network because it requires retransmission of packets due to loss of data. A third method involves limiting the number of packets in the communication medium of a network (i.e., subnet). This method reduces network utility and increases issuance of busy network signals. A fourth method involves sending “choke” packets to the source server to slow down input rate when the server becomes overloaded. This method causes loss of data and requires retransmission of packets.
Moreover, when a server is overloaded, the server rejects a client request by advising the client to turn to another server. This approach requires an already existing client-server session to be terminated and the client application to be modified to support this functionality. Therefore, there is a need in the technology for a method to more efficiently manage server utilization in client-server based networks. The method should conform to existing communication protocols without interfering with established message and signaling structures.